Show unused public properties and methods

It would be nice to have unused detection expanded, capable of detecting unused methods, exports, etc.

Code Example

Shape.js

class Shape {
    constructor() {
        this.color = 'red';
    }

    colorLog() {
        console.log(this.color);
    }
}

export default Shape;

Circle.js

import Shape from "./Shape";

class Circle extends Shape {
  constructor() {
    super();

    // FIXME: description should show as unused in VSCode, as it does in WebStorm.
    this.description = 'A circle shape';
  }

  // FIXME: circleLog should show as unused in VSCode, as it does in WebStorm.
  circleLog() {
    // NOTE: both VSCode and WebStorm have detected an unused variable.
    const num = 2;

    // NOTE: colorLog is being used, so no unused code errors in Shape.js file.
    super.colorLog();
  }
}

// FIXME: export should show as unused in VSCode, as it does in WebStorm.
export default Circle;

VSCode Screen

WebStorm Screen

Start with the Shape.js and Circle.js examples and compare the requested unused-property, method, and export diagnostics with the current behavior in VSCode. Determine the relevant TypeScript language-service entry point and tests before proceeding; done means the unused public members shown in the examples are reported without regressing used members.